Warning signs – Horse Ulcer Symptoms for Gastric vs. Hindgut Ulcers


Treating horse ulcer symptoms all the same way is not the case, understanding the section of the digestive system in which they occur can drastically alter the treatment they require.

The equine digestive system is large and complex. The vast array of functions that this system is responsible for is vital to a horse’s survival. Unfortunately, modern day equine practices often lower its defences and leave it vulnerable to disease.
One of the most common problems a horse’s digestive system can encounter is  ulcers, with an occurrence rate of up to 90% in performance horses and 70% of leisure horses.

Lets explain an ulcer.

Horse ulcers are simply lesions to the mucosal lining of the digestive system and can leave a horse with significant health issues and pain.

Anatomy of the digestive system

The front part of the digestive system or the “foregut” consists of the mouth, esophagus, stomach and small intestine. The back part of the digestive system is called the “hindgut” and consists of the caecum, large colon, small colon, rectum and anus.
Particular sections of the equine digestive system are prone to ulceration – these being the stomach (further divided into two sections) and the colon.

Stomach Anatomy

The stomach has 10% of the capacity of the small intestine. This already suggests to us that horses cannot handle large portions of feed at once. They are much better suited to small amounts fed consumed regularly.
We can divide the stomach into the upper one third and a lower two thirds. The different mucosal linings present in the stomach is important to understand in regards to ulcer diagnosis and treatment. The upper portion is lined by squamous mucosa and has no glands. Ulcers most regularly occur in this portion of the stomach. The lower two thirds is lined by glandular mucosa and contains acid producing glands. Ulcers are less common in this region as it has better defences for its mucosa.

Hindgut Anatomy

The hindgut is about 7 metres (23 feet)  in length with a volume of 140-150 litres (37- 40 gallons) . Horses are known as ‘hindgut fermenters’ as they utilise good bacteria to ferment forage in their colon, creating volatile fatty acids which produce most of the body’s energy. Ulcers occur here as the result of erosion to the mucosa in the caecum and/or colon.

Gastric Ulcers vs. Hindgut Horse Ulcers

Any horse owner out there who has ‘googled’ horse ulcers will be able to tell you that there is a vast amount of information out there but little that is backed up by solid evidence. Most of the treatments we use are either backed up by anecdotal evidence or taken from human studies. Unfortunately, there is still alot we don’t know about all forms of horses ulcers.

Gastric Ulcers

Equine gastric ulcer syndrome ‘EGUS’ is a broad term used to describe any ulceration to the horse’s stomach lining. This can then be further categorised into either ‘Equine Squamous Gastric Ulcer Syndrome’ (ESGUS); ulcers affecting the squamous mucosal lining. Or ‘Equine glandular gastric ulcer syndrome’ (EGGUS) for ulcers affecting the glandular mucosal lining.

Squamous vs. Glandular Mucosa of the Stomach

horse ulcer symptoms Gastric and hindgut ulcersSquamous ulcers – ESGUS

Squamous ulcers will only occur in the upper third of the stomach and indicate increased acid exposure to this area. Ulcers will form quickly and normally occur as a result of low forage or high grain diets as well as stressors like increased training or transportation.

Glandular ulcers – EGGUS

Glandular gastric ulcers will only occur in the lower two thirds of the stomach. These ulcers form slowly and indicate that the mucus coat that protects the glandular tissue has failed and left it exposed to acid. The reason the mucus coat fails is not well understood but could be attributed to many factors including medication, coarse food (alfala hay) or bacteria.

Hindgut Ulcers

Like gastric ulcers, hindgut ulcers occur as a result of damage to the hindgut lining. There are two common causes behind this.

Right dorsal colitis

This often occurs as a result of Non-steroidal anti-inflammatory drug (NSAID) exposure. Phenylbutazone or ‘bute’ is the most commonly used equine NSAID. These medications stop the production of prostaglandins in order to stop pain and inflammation. However, this also affects the mucus production and blood flow that keeps the hindgut lining healthy and protected.

horse ulcer symptoms diet of grain is not good

Reduce intake of high grain diets

Hindgut acidosis

This is simply a raised level of acidity in the hindgut.  High grain diets can be too much for the equine stomach to digest. Excess undigested grain moves on to the hindgut which causes lactic acid production. This increased acidity level is thought to reduce mucus production and leave hindgut lining unprotected from further acid exposure. Parasite burden is also known to cause problem to the hindgut.

Horse Ulcer Symptoms Gastric and HindGut are not disimilar

Unfortunately, gastric and hindgut ulcers can be difficult to diagnose as their symptoms appear similar to other equine diseases; including.

• Poor appetite and weight loss
• Poor performance
• Behavioural changes
• Mild or recurrent colic

Horse Ulcer Symptoms – Differential diagnosis

To date, there are no reliable non-invasive methods that can provide a differential diagnosis between gastric and hindgut ulcers. There are suggestions that horse ulcer symptoms like girth and flank sensitivity are more likely to indicate  hindgut ulcers. Diarrhea, mild or acute and recurrent colic signal a hindgut issue and need immediate attention.  Gastroscopy is the only reliable method for accurate diagnosis of equine gastric ulceration. Because this can be quite expensive, often people will treat with ulcer medication and monitor symptoms changes as a cheaper way of diagnosing.
Keep in mind that the presence or absence of gastric ulceration does not rule out an accompanying hindgut pathology. Yes a horse can have both gastric and hindgut ulcer.

Treatment and prevention

As is often the case – prevention is better than cure. Although we still need more research into all types of equine ulcers it is generally understood that horse management plays a large role in preventing ulcers.

Horse Management as a general treatment and prevention:

It is generally understood that too much acid exposure or poor defences of the mucosal lining against acid are a main reason for ulceration. If you have a horse that has been officially diagnosed with ulcers or you suspect has ulcers you can start treating them simply with a change in management.

Controlling acid production is a good way to prevent ulcers and reduce ongoing acid exposure to existing ulcers allowing them a chance to heal.

Conservative ways of doing this include;

horse ulcer symptoms - give good forage 24/7

Good Forage – good health!

– Increased forage – helps to buffer acid
– Decreased grain – high grain diets can cause hindgut ulcers
– Small meals regularly – constant food in the gut acts as an acid buffer



Although the science behind it is poorly understood we believe that stress plays a huge part in ulceration. So immediate removal of potential stressors is ideal, including;
– Transportation
– Strenuous training
– Competition

ESGUS Treatment:

Omeprazole is the go-to medication for equine squamous gastric ulceration syndrome. It controls gastric acid production thus both preventing further ulceration as well as allowing existing ulcers time to heal. Often it will alleviate pain and encourage a horse to return to normal eating – helping long term management of ESGUS if you are aiming to increase your horse’s forage. Generally speaking, omeprazole will help with help lesions heal within 28 days.

EGGUS Treatment:

Treating EGGUS with omeprazole alone is much less effective than for ESGUS. Instead it is recommended that you treat with both omeprazole and a mucosal protectant like sucralfate. Sucralfate forms a gel when reacting with stomach acid and this forms a protective film over ulcerated or inflamed areas. It is suggested that sucralfate is effective for up to 8 hours.

Hindgut Ulcer Treatment:

A key place to start treatment is by discontinuing or reducing the use of NSAIDs. The use of routine gastric ulcer medications – like omeprazole – will not be successful on hindgut ulcers  However, sucralfate is recommended to bind to and protect ulcers from further acid exposure. It is also suspected that once sucralfate binds to an ulcer it may stimulate further protective chemical production in the area.

Trouble-Shooting Ulcers

Why give sucralfate in conjunction with something else?

Sucralfate doesn’t actually treat ulcers. It simply creates a protective barrier that protects existing ulcers from acid exposure and allows them time to heal as well as protects vulnerable mucous lining. For example, when treating EGGUS, sucralfate is often given in conjunction with omeprazole to control secretion of acid and allows ulcers time to heal.

When do I give sucralfate?

It is recommended that sucralfate be given on an empty stomach – at least 1-2 hours before a meal – as this coats the stomach most effectively. Ideally given 3 times per day as it is effective for only 8hours.
Symptoms can improve before an ulcer is fully healed so it is recommended to follow the dosage instructions .  It is also suggested that other medications not be taken within 2 hours before or after sucralfate. Talk to your vet about how it may interact with other medications you are giving your horse.
As stated previously, we do need to learn more about ulcers and their treatments. A lot of what we know was extrapolated from human or dog studies.

Why doesn’t omeprazole help hindgut ulcers?

It is suspected that omeprazole can make hindgut ulcers worse. As it suppresses stomach acid it can allow undigested food to pass through the stomach into the hindgut. This can cause lactic acid production and worsen hindgut ulcers.

Horse ulcer symptoms can be similar for both types of ulcers in horses.  Learn more about horse ulcer symptoms  here – Equine Gastric ulcer Syndrome.




About Author

Betsy OReilly, Managing Editor of Blog Abler dedicated to Equine Ulcers. Born and bred in country Victoria, Australia, is a lifelong horse owner who has dabbled in Pony Club and Horse Racing. Enjoys hearing and writing about Equine Ulcers.

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